Microwave circuit package and edge conductor structure

ABSTRACT

A ribbon and a bonding wire are connected respectively to a high-frequency input and output of a microwave circuit, the width of the ribbon and/or the thickness of the bonding wire being varied continuously or discontinuously at a portion other than a portion used for bonding. By applying the ribbon and bonding wire to a microwave circuit package including a metallic substrate and sealing therein an MMIC mounted to the metallic substrate, desired high-frequency characteristics of the MMIC can be obtained.

This appln is a continuation of Ser. No. 08/844,921 filed Apr. 22, 1997U.S. Pat. No. 5,936,492.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an improvement in a microwave circuitpackage for sealing therein microwave circuitry having monolithicmicrowave integrated circuits (hereinafter referred to as MMICs), aswell as to ribbons and bonding wires for use in fabricating themicrowave circuit package.

2. Description of the Related Art

Conventionally, bonding wires having uniform diameters along theirlengths, ribbons of uniform thickness and/or mesh ribbons, have beenused for mounting high-frequency devices to a metallic substrate in amicrowave circuit package.

Japanese Patent Laid-Open Publication No. HEI 1-300546 discloses amicrowave circuit package in which electrostatic capacity is providedexternally of an area of an MMIC chip by forming a dielectric layerbetween a metallic substrate and a biasing direct current (DC) terminal.

In such a microwave circuit package, discontinuity of impedance islikely to arise at places where ribbons and bonding wires are provided.As a result, it is likely that components such as MMICs vary in theirbare characteristics after mounting or assemblage thereof, leading todeteriorated characteristics of the components.

Certain occasions arise wherein it is desired that a microwave circuitpackage be fabricated using metallic substrates, MMICs and bonding wireswhich are altered in their materials, while rendering the microwavecircuit package to be compatible with a separate microwave circuitpackage fabricated using the same components but not involving suchchanges in material, by varying the post-mounting high-frequencycharacteristics of the MMIC and so forth.

The post-mounting high-frequency characteristics of the MMICs may bevaried by changing the lengths of the ribbons and bonding wires.However, connection through the bonding wires requires of the latter tobe gently curved in a proper manner. In addition, length alteration ofthe bonding wires is limited due to the limited space within themicrowave circuit package. Another possible approach would be to changethe spacing between the components such as the MMICs to allow alterationof the lengths of the ribbons. However, the space alteration is alsolimited and hence is not an effective solution.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a ribbon and abonding wire which can be connected to an input and an output of amicrowave circuit and allow intentional variation of the frequencycharacteristics of the microwave circuit.

Another object of the present invention is to provide a microwavecircuit package having a metallic substrate and sealing therein an MMICmounted to the metallic substrate, the microwave circuit package furthercomprising a circuit or circuit element having a ribbon and/or a bondingwire assembled thereinto for allowing intentional variation of thefrequency characteristics of the resulting microwave circuit.

According to the present invention, there are provided a ribbon and abonding wire, the width and thickness of which are varied at at least aportion other than a portion thereof used for bonding. Specifically, theribbon width and bonding wire thickness may be varied continuously ordiscontinuously. The ribbon and bonding wire involving such variationmay be used for the connection of a high-frequency input/output of amicrowave circuit sealed in a microwave circuit package.

Effects resulting from the variation of the ribbon width and bondingwire thickness at portions other than portions thereof used for bondingmay be explained as below:

The ribbon and bonding wire have such components as resistance R andreactance X, as well as the total opposition, namely, impedance Z whichis a combination of the former two. Using resistance R and reactance X,the correlations may be represented by Z=(R2+X2)^(½). Magnitude ofreactance X may be represented by X=ωL with respect to inductance L andby X=1/ωC with respect to capacitance C.

Reactance X is a function of frequency f (or angular frequency ω=2πf).In a circuit of high frequency (1-100 GHz) such as a microwave circuit,it is possible to vary reactance X significantly and hence impedance Zby slightly varying inductance L through variation of the ribbon widthand bonding wire thickness.

Accordingly, by varying the width of the ribbon and the thickness of thebonding wire at portions other than portions thereof used for bonding,it becomes possible to intentionally vary the discontinuity of impedancewithin a microwave circuit and to thus vary the frequencycharacteristics of the microwave circuit

Consequently, it also becomes possible to vary impedance in therespective microscopic portions of the ribbon and bonding wire gradually(or continuously) by continuously varying the ribbon width and bondingwire thickness.

By varying the ribbon width and bonding wire thickness discontinuously,it becomes possible to vary impedance in the respective microscopicportions of the ribbon and bonding wire suddenly (or in a phasedfashion).

In a preferred form, the MMIC sealed within the microwave circuitpackage according to the present invention is provided with ahigh-frequency compensating circuit positioned closely to the bondingportions of the ribbon and bonding wire. Apart from varying thefrequency characteristics of the microwave circuit through the variationof the ribbon width and bonding wire thickness, provision of such ahigh-frequency compensating circuit also makes it possible toindependently vary the frequency characteristics of the microwavecircuit in that impedance can be regulated using the high-frequencycompensating circuit. The high-frequency compensating circuit may becomprised of an impedance regulating stub. As a result, it becomepossible to delicately vary the frequency characteristics of themicrowave circuit using the ribbon, bonding wire and the high-frequencycompensating circuit having different characteristics.

Alternatively, the high-frequency input/output of the microwave circuitwithin the microwave circuit package may be connected by means of theribbon varied in thickness at at least a portion other than a portionthereof used for bonding. By varying the thickness of the ribbon at aportion other than a portion thereof used for bonding, it becomespossible to intentionally vary the discontinuity of impedance within themicrowave circuit so as to effect the intentional variation of thefrequency characteristics of the microwave circuit.

The high-frequency input/output of the microwave circuit within themicrowave circuit package according to the present invention maydesirably be connected by means of the ribbon varied in width at aportion other than a portion thereof used for bonding and having opposedends narrower than the widths of the microwave circuit high-frequencyinput/output ends to which the ribbon is to be bonded. By varying thewidth of the ribbon at a portion other than a portion thereof used forbonding, it becomes possible to intentionally vary the discontinuity ofimpedance in the microwave circuit to thereby intentionally vary thefrequency characteristics of the microwave circuit. By making the widthsof the opposed ribbon ends narrower than the widths of thehigh-frequency input/output ends to which the ribbon is to be bonded,positioning of the ribbon upon bonding thereof becomes easy, leading toreduced production costs of the microwave circuit package.

The microwave circuit package according to the present inventionincludes a support member disposed on the metallic substrate forsupporting the ribbon thereon. By disposing the support member on themetallic substrate for supporting the ribbon, increased mechanicalstrength may be imparted to the ribbon, thus resulting in increasedreliability of the microwave circuit. When there is a height differencebetween the MMICs and other components, a sloped surface correspondingto the height difference may be provided on the support member so thatthe ribbon can be positioned to lie along the sloped surface, thuscompensating for the height difference. Further, by varying the materialof the support member, it becomes possible to vary capacitance betweenthe ribbon and metallic substrate. This also enables the variation ofthe frequency characteristics of the microwave circuit.

The ribbon may have a width enlarged at an edge of the MMIC to the widthof the strip conductor while the opposed ends. thereof are arranged suchthat the one proximate to the MMIC has a width substantially equal tothe width of the high-frequency input of the MMIC and the otherproximate to the dielectric substrate has a width substantially equal tothe width of the strip conductor. By varying the width of the ribbon ata portion other than a portion thereof used for bonding, it becomespossible to intentionally vary the discontinuity of impedance within themicrowave circuit and hence the frequency characteristics of themicrowave circuit. Particularly, by increasing the width of the ribbonat an edge of the MMIC to the width of the strip conductor, it becomespossible to obtain an arrangement similar to the arrangement in whichthe strip conductor extends to the high-frequency input/output ends ofthe MMIC. The thus obtained arrangement produces improved post-mountingfrequency characteristics compared to at least the arrangement whereinthe ribbon of uniform width equal to the widths of the high frequencyinput/output ends of the MMIC is used for connection.

Preferably, the microwave circuit package according to the presentinvention includes a high-frequency compensating circuit disposed on thedielectric substrate proximately to the bonding portion of the ribbon.Apart from varying the frequency characteristics of the microwavecircuit through the use of the ribbon, provision of such ahigh-frequency compensating circuit also enables independent variationof the frequency characteristics of the microwave circuit in thatimpedance can be regulated through the use of the high-frequencycompensating circuit. As a result, it become possible to delicately varythe frequency characteristics of the microwave circuit through the useof the ribbon and the high-frequency compensating circuit havingdifferent characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional objects, advantages and features of the present inventionwill become apparent from the following description and appended claims,when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic plan view illustrating a microwave circuit packageaccording to the present invention;

FIG. 2 is a schematic cross-sectional view taken along line A—A of FIG.1, showing the microwave circuit package with DC terminals and bondingwires removed;

FIG. 3A is an enlarged plan view illustrating an MMIC with itshigh-frequency input connected to a strip conductor on a dielectricsubstrate by means of a ribbon;

FIG. 3B is a schematic cross-sectional view of FIG. 3A;

FIG. 4A is an enlarged plan view similar to FIG. 3A illustrating ahigh-frequency compensating circuit disposed on the dielectricsubstrate;

FIG. 4B is a schematic cross-sectional view of FIG. 4A;

FIGS. 5A, 5B, 5C, 5D schematically illustrate various ribbonconfigurations;

FIG. 6 is a view illustrating schematically a bonding wire having aflattened portion;

FIG. 7 is a view illustrating schematically a bonding wire having twoflattened portions;

FIG. 8 is a view schematically illustrating a bonding wire with acorrugated portion;

FIG. 9 is a view schematically illustrating a bonding wire having aflattened portion and a corrugated portion; and

FIG. 10 is a view schematically illustrating a bonding sire with acorrugated portion on one surface thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 2, a microwave circuit package 10 according tothe present invention includes a metallic substrate 3 and sealsmonolithic microwave integrated circuits (MMICS) 11, 12 disposed on themetallic substrate 3.

The metallic substrate 3 also seals a dielectric substrate 17 anddielectric elements 19 mounted to the metallic substrate 3. Thedielectric substrate 17 is provided on a surface thereof with a stripconductor 17 b. The metallic substrate 3, dielectric substrate 17 andstrip conductor 17 b jointly provide microstrip lines.

The metallic substrate 3 is formed from Kovar or the like and alsoserves as a heat sink. An upper cover 6 and sides 5 are formed from adielectric material. The MMICs 11, 12 are formed from GaAs while thedielectric substrate 17 is formed from ceramics such as aluminaceramics.

The MMIC 11 has a plurality of biasing DC terminals 34, 35 which areconnected thereto by means of their respective bonding wires 44, 45 andextend through the metallic substrate 3 in an electrically insulatedmanner for supplying a given biasing voltage to the MMIC 11.

Similarly, the MMIC 12 has a plurality of biasing DC terminals 36, 37which are connected thereto by means of their respective bonding wires46, 47 and extend through the metallic substrate 3 in an electricallyinsulated manner for supplying a given biasing voltage to the MMIC 12.

High-frequency input of the MMIC 11 is connected to the strip conductor17 b on the dielectric substrate 17 by means of a ribbon 11 e.High-frequency outputs of the MMIC 11 are connected to their respectiveRF terminals 11 f, 11 g via bonding wires 40.

High-frequency input of the MMIC 12 is connected to the strip conductor17 b on the dielectric substrate 17 via a ribbon 12 e. Twohigh-frequency outputs of the MMIC 12 are connected to their respectiveRF terminals 12 f, 12 g by means of bonding wires 42.

The strip conductor 17 b and RF terminal 17 a on the dielectricsubstrate 17 are interconnected through a bonding wire 44.

Using the above-described microstrip lines, various circuits and/orcircuit elements may be fabricated. For example, a distributor fordistributing high-frequency signals can be formed using such microstriplines to thereby reduce the RF terminals in number.

With the DC terminals 34, 35, 36, 37 being arranged to extend verticallyrelative to the surface of the metallic substrate 3 and RF terminals 11f, 11 g, 12 f, 12 g, 17 a being disposed at opposite edges of themetallic substrate 3 and extending horizontally within a plane of thesurface of the base plate 3, the microwave circuit package 10 can beplaced in close proximity to a companion microwave circuit package,whereby highly dense microwave circuit package assemblage is enabled.

FIG. 3A illustrates in top plan a ribbon 11 e connecting thehigh-frequency input terminal 11 s of the MMIC 11, forming part of thelines, with the strip conductor 17 b on the dielectric substrate 17, andits peripheries. FIG. 3B is a cross-sectional view illustrating theribbon 11 e and its peripheries. The ribbon lie is supported on asupport member 18 which is formed of a material such as resins anddisposed on the metallic substrate 3.

Ends of the ribbon 11 e are bonded respectively to the high-frequencyinput 11 s and strip conductor 17 b by thermal pressure bonding orultrasonic pressure bonding. The width of the ribbon end on the MMIC 11side is equal to the width of the high-frequency input 11 s while theribbon end on the dielectric substrate 17 side is equal to the width ofthe strip conductor 17 b. The width of the ribbon 11 e is increased atthe edge of the MMIC 11 to correspond to the width of the stripconductor 17 b. Stated otherwise, the ribbon 11 e has altered or variedwidths at portions other than the portions to be subjected to bonding.Alternatively, the ribbon width on the MMIC 11 side may be smaller thanthe width of the high-frequency input 11 s whilst the ribbon end on thedielectric substrate 17 side may be smaller than the width of the stripconductor 17 b. That is, the end widths of the ribbon 11 e may besmaller than the widths of the high-frequency input and output ends towhich the ribbon 11 e is to be bonded.

FIG. 4A and FIG. 4B illustrate an embodiment of the microwave circuitpackage shown in FIG. 3A and FIG. 3B, in which the dielectric substrate17 is provided with an impedance regulating stub 17 z serving as ahigh-frequency compensating circuit. On the dielectric substrate 17 of amicrostrip line for effecting high-frequency inputting and outputting,there is provided a high-frequency compensating circuit in closeproximity to the bond position of the ribbon 11 e. FIG. 4C shows analternative form of compensating circuit wherein the ribbon has oposedends of a width narrower than the central portion 11 e. Thehigh-frequency compensating circuit may comprise a bonding pad and bedisposed on the MMIC 11.

FIG. 5A-FIG. 5C illustrate various configurations of the microwavecircuit ribbon according to the present invention, as seen in top plan,while FIG. 5D shows the ribbon in side elevation.

Shown in FIG. 5A is a ribbon corresponding to the ribbons 11 e, 12 edescribed in relation to FIG. 1 through FIG. 4 and having a width varieddiscontinuously.

The ribbon shown in FIG. 5B has ends equal in width to the ends of theribbon shown in FIG. 5A, and a central part wider than that of thelatter ribbon so that the width of the former ribbon is longitudinallyvaried discontinuously.

The ribbon shown in FIG. 5C is continuously varied in widthlongitudinally but has ends equal in width to the ends of the ribbonshown in FIG. 5A, thus providing a trapezoidal configuration.

The thickness of the ribbons shown in FIG. 5A-FIG. 5C may be varied sothat a stepped portion is provided as shown in FIG. 5D. By varying thethickness of the ribbons at portions other than bonding portions thereofto provide such a stepped portion, longitudinal positioning of theribbons upon bonding thereof becomes easy. Alternatively, the ribbonsmay-have thicknesses uniform lengthwise.

FIG. 6 illustrates a bonding wire 40 as an example for connecting thehigh-frequency output and RF terminal 11 f of the MMIC 11.

As shown in FIG. 6, the bonding wire 40 has a thickness or diameteraltered at portions other than the bonding portions thereof. The bondingwire has a flattened portion 40 a formed, for example, by pinching witha small-sized pair of tweezers. The flattened portion 40 a has asubstantially oval cross-section. The bonding wire 40 may be altered inconfiguration such that it has two flattened portions 40 a, 40 a atportions other than the bonding,portions thereof, as shown in FIG. 7.

FIG. 8 illustrates an altered form of the bonding wire 40 in which partof the bonding wire 40 is corrugated as at 40 b. Such a corrugatedportion can be formed, for example, by pinching a desired part of thewire with saw-teethed portions at tip ends of a small-sized pair oftweezers.

In a further altered form, the bonding wire 40 has a thickness varieddiscontinuously lengthwise such that it has a corrugated portion 40 c onone side and a flat or straight portion on the other, the corrugated andstraight portions being obtained by causing a desired part of thebonding wire to be pinched between a saw-teethed portion on one side ofa tip end and a straight portion on an opposed side of a companion tipend of a pair of tweezers (see FIG. 10).

FIG. 9 illustrates a still further alteration of the bonding wire 40 inwhich both a flattened portion 40 a and a corrugated portion 40 brespectively shown in FIG. 6 and FIG. 8 are provided.

The RF terminals 11 f, 11 g, 12 f, 12 g and high-frequency output endsof the MMICs 11, 12 according to the present invention may beinterconnected by means of beam leads of gold or like material, or theribbons as used at the high-frequency input ends. Similarly, thehigh-frequency output ends and strip conductor 17 b of the MMICs 11, 12may be interconnected through the above-described inventive bondingwires. The RF terminals 11 f, 11 g, 12 f, 12 g, 17 a may be arranged toextend vertically with respect to the surface of the metallic substrate3 like the DC terminals 34-37.

The present invention may also be applied to the radar module andantenna apparatus as proposed in Japanese Patent Application No. HEI7-239311. For example, a plurality of MMICS, each including fourhigh-frequency field effect transistors (FETS) and two mixers, may bemounted to the package so as to provide a multichip circuit.

As thus far explained, the ribbons, bonding wires and/or microwavecircuit package employing the same according to the present inventionallow intentional alteration or variation of discontinuity of impedancewithin the microwave circuit in that the width of the ribbons and/or thethickness of the bonding wires are altered at portions other than thebonding portions thereof, whereby the frequency characteristics of themicrowave circuit can be varied intentionally by virtue of the ribbons,and bonding wires incorporating such intentional alterations.

Also, impedance in the respective microscopic portions of the ribbonsand bonding wires and hence the microwave circuit package according tothe present invention can be varied gradually (or continuously).

Further, impedance in the respective microscopic portions of the ribbonsand/or the bonding wires and hence the microwave circuit packageaccording to the present invention can be effectively varied suddenly(or in a phased manner) since the width of the ribbons and/or thethickness of the bonding wires are varied discontinuously.

Additionally, in the microwave circuit package according to the presentinvention, the frequency characteristics of the microwave circuits canbe varied not only by the ribbons and/or the bonding wires but also bythe high-frequency compensating circuit provided for impedanceregulation. As a result, it becomes possible to make slight changes inthe frequency characteristics of the microwave circuits by means of thehigh-frequency compensating circuit and the ribbons and/or bonding wireshaving different characteristics.

Since the microwave circuit package according to the present inventionemploys the inventive ribbons varied in thickness at portions other thanthe bonding portions thereof, it becomes possible to intentionally varythe discontinuity of impedance in the microwave circuit, thus enablingintentional variation of the frequency characteristics of the microwavecircuit.

Also, since the microwave circuit package according to the. presentinvention employs the ribbons varied in width at portions other than thebonding portions thereof, it becomes possible to intentionally vary thediscontinuity of impedance in the microwave circuit, thus enablingintentional variation of the frequency characteristics of the microwavecircuit. In particular, since the ribbons are provided with oppositeends having widths narrower than the widths of the high-frequencyinput/output ends of the ribbons at which the latter are to be bonded,positioning of the ribbons upon bonding thereof becomes easy, therebyreducing the production costs of the microwave circuit package.

Furthermore, in the microwave circuit package according to the presentinvention, the support member supporting the ribbons thereon is disposedon the metallic substrate. As a result, it becomes possible to impartmechanical strength to the ribbons, thus resulting in increasedreliability of the microwave circuit. When there is a height differencebetween the high-frequency inputting/outputting MMICs or the like, asloped surface corresponding to the height difference may be provided onthe support member so that the ribbons can be positioned to lie alongthe sloped surface, thus compensating the height difference. By alteringthe material of the support member, it also becomes possible to vary thecapacitance between the ribbons and the metallic substrate. Utilizationof this further enables varying of the frequency characteristics of themicrowave circuit.

In the microwave circuit package according to the present invention, byintentionally varying the width of the ribbons at portions other thanthe bonding portions thereof, it becomes possible to intentionally varythe discontinuity of impedance within the microwave circuit, wherebyintentional variation of the frequency characteristics of the microwavecircuit is enabled. Particularly, by increasing the ribbon width at theedges of the MMICs up to the width of the strip conductor, it becomespossible to obtain an arrangement similar to the one in which the stripconductor extends up to the high-frequency input/output ends of theMMICs. The thus-obtained arrangement provides increased post-mounthigh-frequency characteristics of the MMICs compared to at least thearrangement in which the ribbons of uniform width equal to the width ofthe high-frequency input/output ends of the MMICs are used forconnection.

As already explained above, in the microwave circuit package accordingto the present invention, the frequency characteristics of the microwavecircuit can be varied via the ribbons. Such frequency variation can alsobe achieved through impedance regulation using the high-frequencycompensating circuit. Thus, subtle or delicate variation of thefrequency characteristics of the microwave circuit is enabled by usingthe ribbons and high-frequency compensating circuit having differentcharacteristics.

Moreover, since the high-frequency compensating circuit in the microwavecircuit package according to the present invention is comprised of theimpedance regulating stub disposed in close proximity to the bondingportions of the ribbons and/or the bonding wires, impedance regulationcan be. effected on the MMIC side, as well as on the dielectricsubstrate side.

The foregoing discussion discloses and describes merely exemplaryembodiments of the present invention. One skilled in the art willreadily recognize from such discussion, and from the accompanyingdrawings and claims, that various changes, modifications and variationscan be made therein without departing from the spirit and scope of theinvention as defined in the following claims.

What is claimed is:
 1. A microwave circuit package including a metallicsubstrate and sealing therein a microwave circuit mounted to saidmetallic substrate, said microwave circuit package further comprising: adielectric substrate having a strip conductor having a width and mountedto said metallic substrate in a sealed fashion; a ribbon having a widthconnected to a high frequency input of said microwave circuit; saidribbon having opposed ends and a central portion, one of said endsproximate to said microwave circuit having a width substantially equalto the width of said high frequency input of said microwave circuit, theother of said opposed ends proximate to said dielectric substrate havinga width substantially equal to the width of said strip conductor; andsaid central portion between said opposed ends having a width beingvaried intermediate the ends thereof at least a portion other than abonding portion thereof, the bonding portion being at an end thereof,wherein the central portion of said ribbon has a thickness greater thanthe thickness of each of said ends; and a high frequency impedanceregulating compensating circuit disposed on said microwave circuit inclose proximity to the bonding portion of said ribbon, the bondingportion being at an end thereof.
 2. A microwave circuit packageincluding a metallic substrate and sealing therein a microwave circuitmounted to said metallic substrate, said microwave circuit packagefurther comprising: a dielectric substrate having a strip conductorhaving a width and mounted to said metallic substrate in a sealedfashion; a ribbon having a width connected to a high frequency input ofsaid microwave circuit; said ribbon having opposed ends and a centralportion, one of said opposed ends proximate to said microwave circuithaving a width substantially equal to the width of said high-frequencyinput of said microwave circuit, the other of said opposed endsproximate to said dielectric substrate having a width substantiallyequal to the width of said strip conductor; and said central portionbetween said opposed ends having a thickness greater than the thicknessof each of said ends, a high frequency impedance regulating compensatingcircuit disposed on said dielectric substrate in close proximity to thebonding portion of said ribbon, the bonding portion being at an endthereof.
 3. The microwave circuit package according to claim 2, whereinthe high frequency impedance regulating compensating circuit comprisesan impedance regulating stub.
 4. The microwave circuit package accordingto claim 2, further comprising a support member disposed on the metallicsubstrate for supporting the ribbon thereon.